Researchers at the Centers for Disease Control and Prevention (CDC) found that of 642 U.S.-bound Burmese children, 90 percent had some amount of lead in their blood. Overall, 5 percent had lead poisoning -- including nearly 15 percent of children younger than 2.

High lead exposure is especially dangerous for young children, since it can permanently damage their developing brains.

In the U.S. and other developed countries, children's lead exposure dropped substantially after the heavy metal was removed from gasoline, house paints and other products. But studies have found that lead poisoning is still fairly common among refugee children who come from countries where lead exposure is a bigger problem.

For the new study, CDC researchers focused on Burmese children who were living in one of three Thailand refugee camps before coming to the U.S.

In 2008, there had been reports of high lead poisoning rates among children who were resettled in the U.S. after living in those camps -- suggesting that at least some of their lead exposure happened in the camps.

The CDC researchers found that of 642 refugee-camp children tested over two months in 2009, nearly all had some detectable lead in their blood. And the number with lead poisoning was several times higher than what's seen in U.S. children.

Of children younger than 6 -- the most at-risk age group -- about 7 percent had lead poisoning. In the U.S., it's estimated that 1 percent of kids in that age range suffer lead poisoning.

What's more, refugee children younger than 2 had a lead poisoning rate of 14.5 percent.

Children were considered to have lead poisoning if their levels were at least 10 micrograms of lead per deciliter of blood. That's the CDC's current threshold.

A federal advisory panel, however, just recommended that the threshold be lowered to 5 micrograms. It has long been known that even lead exposures lower than 10 micrograms per deciliter are linked to lower IQ in children.

The CDC already recommends that all refugee children have their lead levels checked within three months of arriving in the U.S.

CAR BATTERIES, REMEDIES, ANEMIA AT FAULT?

The current study is the first to test children's lead concentrations before they come to the U.S., according to the CDC researchers, led by Dr. Tarissa Mitchell.

And the findings point to some factors that put children at particular risk while they're still in refugee camps.

Many children with lead poisoning were exposed to car batteries in their homes, which families used to generate power for electronic items. Children younger than 2 were particularly likely to have touched or "mouthed" the batteries.

Young children who'd been given traditional remedies at the camps were also at increased risk of lead poisoning, the researchers found.

Past studies have found that some traditional medicines are contaminated with lead. When Mitchell's team tested seven remedies sold at the Thai refugee camps, they found that one -- a "multipurpose infant remedy" called Gaw Mo Dah -- had lead levels far above what's considered acceptable in foods in the U.S.

But the biggest factor seemed to be anemia, which is most often caused by iron deficiency. Anemia is known to make children more vulnerable to lead poisoning.

The CDC recommends that when refugee children in the U.S. are tested for lead levels, they also be screened for anemia and have a "nutritional assessment."

But the current findings also show that efforts are needed in the refugee camps themselves, according to Mitchell's team.

The Thai camps, they say, have already started educational campaigns to warn families about the dangers of lead exposure.

Once children are in the U.S., the CDC researchers say, families should be placed in "lead-safe" housing. And after their first lead test, children younger than 6 should be re-tested within six months of settling into permanent housing.

Burma, also known as Myanmar, was under military rule until last year, when a civilian government was installed following elections. Each year since 2007, up to 15,000 Burmese refugees have resettled in the U.S. from camps in Thailand.

SOURCE: bit.ly/zNNv7x Pediatrics, online January 16, 2012.

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